Print all lines containing the keyword test:

grep test file.txt

Create a file that has all the keywords, one per line and run:

grep -f keywords.txt file.txt

Process a file line by line, exit if the line is found:

while read line; do 
  echo $line | grep test && break; 
done < file.txt

while read line; do let c++; echo $line | grep test >/dev/null; 
  if [[ $? == 0 ]] ; then echo Match for line $c : $line;
  else echo No match for line $c; fi  
done < file.txt